Active, passive protection and building codes

Several resources provide guidance on both active and passive fire protection.

Kathleen Roach, CET, CFPS, Interface Engineering, Portland, Ore.

07/14/2014

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The building and fire codes do not call out specific fire safety goals; their main objective is life safety of occupants and firefighters. Preservation of the primary structure and neighboring structures is a resulting benefit.

Some occupancies, such as I-occupancies (prisons, hospitals), where occupants may be unable to evacuate themselves due to incarceration or physical disabilities, limit fire protection strategies to “defend in place” and require both active and passive fire protection.

Because of the documented effectiveness of functioning and adequate fire sprinkler systems, the IBC allows a reduction of some passive fire protection systems in some occupancies where full fire sprinkler systems are installed throughout a building. These usually mean full NFPA 13 systems. If a residential building of four stories or less is otherwise eligible for an NFPA 13R system, if a reduction of the passive systems is desired due to the installation of a fire sprinkler system, the IBC, in most but not all instances, requires that the fire sprinklers be installed “throughout” the building, meaning an upgrade to an NFPA 13 system. Keep in mind that local authorities having jurisdiction (AHJ) may consider that many of the alternate methods of fire protection identified in IBC 904 (clean agent systems and the like) do not qualify for these “trade-offs.”

Where fire sprinklers are installed, some of the passive system trade-offs allowed by the 2012 IBC include the following. State and local amendments may affect them.

Building height increases of 1 story and up to 20 ft. (IBC 504.2).

Building area increases of up to 300% for 1-story buildings and 200% increases for multiple-story buildings (IBC 506.3).

Unlimited areas in 1- and 2-story buildings for group B, F, M, and S buildings (IBC 507.3 and 507.4).

Occupancy separations: Up to a 1-hour reduction in the fire-resistance rating of fire separation walls (IBC 508.4).

Exterior wall openings: Sprinklered maximum allowable area of unprotected openings is allowed to be the same as for protected openings (IBC Table 705.8).

Exterior wall openings: Where buildings are provided with sprinklers and water curtains are installed at the exterior, the protection requirements of openings in an exterior wall may be deleted (IBC 705.8.2).

Exterior wall openings: Flame barriers protecting window separations of 5 ft or less may be deleted where sprinklers are installed throughout (IBC 705.8.5).

High-rise buildings: Reductions in many fire-resistance ratings where sprinkler floor control valves are supervised and water flow initiating devices connected to the fire alarm system are provided (IBC 403.2.1).

High-rise buildings: Fire barrier walls enclosing vertical shafts (other than exit enclosures and elevator hoistway enclosures) are allowed to be reduced to a 1-hour fire-resistance rating where automatic sprinklers are installed at the top and at alternate floor levels within the shafts (IBC 403.2.1.2).

NFPA’s “Fire Protection Handbook” is another excellent source of further information on active and passive fire protection.

Kathleen Roach is associate principal and senior fire/life safety designer at Interface Engineering. She has approximately 20 years of experience in fire protection design and strong technical knowledge of codes, standards, and recommended practices. Her work includes specification and design for fire suppression systems and fire/life safety reviews.